Atoms, Molecules, Water, and Biological Macromolecules

Flashcards covering general chemistry, chemical bonds, water properties, pH balance, and major biological macromolecules based on human anatomy lecture notes.

What are the three categories of matter found in the human body?

Solid, liquid, and gas.

Which six major elements make up 99% of the human body?

Oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus.

Which six minor elements compose approximately 1% of the human body?

Sulfur, potassium, sodium, chlorine, magnesium, and iron.

What are the two scientific models used to visualize the structure of an atom?

The shell model and the cloud model.

Which subatomic particles are located in the nucleus of an atom?

Protons and neutrons.

What is the atomic mass and electrical charge of a proton?

A proton has an atomic mass of $1$ atomic mass unit and a positive charge ($+1$).

What is the mass and charge of an electron?

An electron has a negligible atomic mass unit and a negative charge ($-1$).

What does the atomic number of an element represent?

The number of protons in an atom of that element.

How is the atomic mass number of an element calculated?

The total number of protons plus neutrons in the atom.

How do you calculate the number of neutrons in an element using periodic table shorthand?

Subtract the atomic number (bottom number) from the atomic mass number (top number).

What defines an isotope?

An atom of an element that has a different number of neutrons than protons, altering its atomic mass while keeping the proton number and charge unchanged.

How many protons and neutrons are in carbon-14?

$6$ protons and $8$ neutrons.

What is the octet rule in chemical bonding?

Atoms are most chemically stable when their outermost valence shell contains $8$ electrons (except the first shell, which holds $2$).

Why are noble gases in column 8 of the periodic table chemically unreactive?

They already have a full valence shell containing $8$ electrons.

What is a cation?

A positively charged ion formed when an atom loses or donates an electron.

What is an anion?

A negatively charged ion formed when an atom gains an electron.

How is an ionic bond formed?

By the complete donation of an electron from one atom to another, resulting in an attraction between a cation and an anion.

What is a covalent bond?

A chemical bond formed when two or more atoms share electrons.

What are isomers?

Molecules that have the exact same molecular formula but different structural formulas (arrangements).

How do nonpolar covalent bonds differ from polar covalent bonds?

Nonpolar covalent bonds share electrons equally, while polar covalent bonds share electrons unequally due to differences in electronegativity.

How does electronegativity change across the periodic table?

Electronegativity increases across the periodic table from left to right.

What is a hydrogen bond?

A weak attraction between a hydrogen atom covalently bound to an electronegative atom (like oxygen or nitrogen) and another electronegative atom.

What defines an inorganic substance?

Any substance or molecule that does not contain carbon.

What are the four primary functions of liquid water in the human body?

Transportation of substances, lubrication between structures, cushioning against sudden impacts, and excretion of waste.

What is specific heat?

The energy necessary to raise the temperature of $1$ gram of a substance by $1$ degree.

Why is water's high specific heat essential for human homeostasis?

It allows the body to absorb large amounts of metabolic heat without experiencing a drastic increase in temperature.

What is the difference between hydrophilic and hydrophobic substances?

Hydrophilic substances readily dissolve in water, while hydrophobic substances do not easily dissolve in water.

What does it mean for a molecule to be amphipathic?

It contains both hydrophilic (polar) and hydrophobic (nonpolar) regions.

How does an acid affect the hydrogen ion concentration and pH of a solution?

An acid increases the hydrogen ion ($H^+$) concentration, which lowers the pH below $7$.

What is the optimal pH range for most human body functions?

Between $6$ and $8$.

How do chemical buffers maintain acid-base balance in the body?

They absorb hydrogen ions when acid is added or release hydrogen ions when a base is added to bring the pH back toward neutral.

What happens during a dehydration synthesis reaction?

Water is removed to form a chemical bond that builds a larger macromolecule (anabolism).

What happens during a hydrolysis reaction?

Water is added to break a chemical bond and split a macromolecule into smaller components (catabolism).

Which class of biological macromolecules is NOT composed of polymers?

Lipids.

What are the structural components of a triglyceride?

One glycerol backbone and three fatty acid chains.

What is the structural difference between a saturated fatty acid and an unsaturated fatty acid?

Saturated fatty acids contain only single bonds and max hydrogen atoms; unsaturated fatty acids contain one or more double bonds.

What structural components make a phospholipid amphipathic?

A polar (hydrophilic) phosphate head and two nonpolar (hydrophobic) fatty acid tails.

What is the characteristic structure shared by all steroids?

A four-carbon ring structure.

What is the monomer unit of a carbohydrate?

A monosaccharide.

In what form is glucose stored in long polysaccharide chains in the human liver?

Glycogen.

What three components make up a single nucleotide?

A five-carbon sugar, a phosphate group, and a nitrogenous base.

What are three key structural differences between DNA and RNA?

DNA contains deoxyribose sugar, is double-stranded, and uses thymine ($T$); RNA contains ribose sugar, is single-stranded, and uses uracil ($U$).

What base pairs with adenine ($A$) in RNA?

Uracil ($U$).

Why is ATP considered a modified nucleotide?

It consists of a ribose sugar and an adenine base, but has three phosphate groups instead of one.

What is the monomer unit of a protein?

An amino acid.

What type of chemical bond links amino acids together in a polypeptide chain?

A peptide bond.

What defines the primary structure of a protein?

The linear sequence of amino acids linked together by peptide bonds.

What are the two common shapes found in a protein's secondary structure?

An alpha helix and a beta sheet.

How do fibrous proteins differ from globular proteins in shape and function?

Fibrous proteins are linear/extended and provide structural support; globular proteins are compact/spherical and perform functional roles like acting as enzymes or hormones.

What is protein denaturation?

The disruption or unfolding of a protein's tertiary three-dimensional structure due to factors like high temperature or extreme pH, causing loss of function.